The most common type of display device requires the individual display elements of the display device to be refreshed a number of times per second to maintain the picture being displayed. If power is removed from the display device, then no picture can be displayed on the display device. Another type of display device is one that only requires that power be provided to the display device when the picture displayed on the device is modified or changed. Otherwise, a static image remains displayed on the display device substantially indefinitely even in the absence of power to the display device, although power may still be needed for backlighting purposes.
The latter type of display device includes those implemented using bi-stable display elements. Bi-stable display elements have an on state, in which the display element is on and displaying image data, and an off state, in which the display element is off and not displaying image data. Because such bi-stable display elements have just two states, a number of independently addressable elements may be needed to implement a single pixel of a display device. For instance, to implement a single color of a pixel having three bits, or eight levels, of color depth, three such bi-stable display elements may be needed, since 23 bits equals eight levels.
To realize a display device using such bi-stable display elements in which each pixel includes three colors, red, green, and blue, and each sub-pixel has eight, sixteen, or more tonal levels, a large number of bi-stable display elements may be needed. This in turn means that a large number of addressable lines have to be connected to the display elements, since each display element is independently addressable. The resulting display device, however, may be difficult to cost effectively manufacture, owing to the large number of bi-stable display elements and the large number of addressable lines connected to these elements.